The present invention relates to a solid-state laser device, and in particular, to a solid-state laser device in which output of a semiconductor pumped solid-state laser device is controlled.
Referring to FIG. 5, description will be given below on general features of a semiconductor pumped solid-state laser device.
In FIG. 5, reference numeral 1 denotes a light emitting unit comprising a single diode or a plurality of laser diodes for emitting a laser beam with a wavelength of λ as an excitation light, and the numeral 2 denotes a resonator for outputting a laser beam with a wavelength of λ1.
The resonator 2 primarily comprises a reflection mirror 3, an output mirror 4 disposed at a position opposite to the reflection mirror 3, and a laser crystal 5 positioned on an optical axis of the output mirror 4 and the reflection mirror 3. On the reflection mirror 3 and the output mirror 4, there are formed a dielectric reflection film 6 and a dielectric reflection film 7.
A half-mirror 8 is provided on an optical axis on an output side of the resonator 2. The half-mirror 8 splits a part of the laser beam outputted from the resonator 2 and enters the laser beam to a monitor photodetector 9. A photodetection signal from the monitor photodetector 9 is inputted to a control unit 11. The control unit 11 controls the light emitting unit 1 so that intensity of an output light from the resonator 2 can be controlled and that output conditions of a pulsed light, a continuous light, etc. can be controlled.
As the laser crystal 5, Nd:YVO4 or YAG (yttrium aluminum garnet) doped with Nd3+ ions is used.
In the semiconductor pumped solid-state laser device described above, when the light emitting unit 1 is turned on, an excitation light is projected to the resonator 2 through the reflection mirror 3. The excitation light passes through the laser crystal 5 and is pumped between the dielectric reflection film 6 and the dielectric reflection film 7 and is amplified. Then, a laser beam 12 with the wavelength λ1 is outputted through the output mirror 4.
The laser beam 12 is projected through the half-mirror 8 and is split by the half-mirror 8, and a part of the laser beam 12 enters the monitor photodetector 9. When the monitor photodetector 9 receives the part of the laser beam 12, the photodetection signal is issued. Then, the photodetection signal is inputted to the control unit 11. Based on the photodetection signal, the control unit 11 controls the light emitting unit 1 so that intensity and output condition of the laser beams 12 can be controlled to the predetermined intensity and condition.
In an application previously filed (Japanese Patent Application 2002-335683), the present applicants proposed a solid-state laser device provided with a plurality of resonators, which commonly share an optical axis.
The solid-state laser device as proposed above is advantageous in that output of the laser beam can be increased, or a plurality of laser beams with different wavelengths can be outputted, and the device can be designed in simple structure.
In order that the desired output condition of the laser beam is obtained by a solid-state laser device with a plurality of resonators, the resonators must be respectively and independently controlled.